In this tutorial, we first look at functions defined by a rule (or formula). We then look at more general functions defined with a domain and codomain, and we use the graph of a function to find the range of the function.

Most Algebra courses (like this one) are preparation for a Calculus course, and so we also look at the typical Calculus definition of a function where the function is simply specified by a rule. The domain is then the largest subset of the set of all real numbers that is compatible with the rule of the function, and the codomain is the set of all real numbers.